High
F (Ignition fault shown) on Saunier Duval Thema F 30 E Plus

Your boiler is failing to light the internal flame needed to heat your water and home.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description

The green running light will change to a red flashing light and the display will flash the letter ‘F’ with the type of fault. (Ignition fault)

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Related fault codes

F4View →F5View →

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